1. Technical Field
The present invention relates to three-dimensional (3D) visualization of medical images, and more particularly, to a system and method for determining a location and a direction for viewing a protrusion, such as a colonic polyp, in a medical image.
2. Discussion of the Related Art
In the field of medical imaging, various systems have been developed for generating medical images of various anatomical structures of individuals for the purposes of screening and evaluating medical conditions. These imaging systems include, for example, computed tomography (CT) imaging, magnetic resonance imaging (MRI), positron emission tomography (PET), etc. Each imaging modality may provide unique advantages over other modalities for screening and evaluating certain types of diseases, medical conditions or anatomical abnormalities, including, for example, colonic polyps, aneurysms, lung nodules, calcification on heart or artery tissue, cancer micro-calcifications or masses in breast tissue, and various other lesions or abnormalities.
For example, CT imaging systems can be used to obtain a set of cross-sectional images or two-dimensional (2D) “slices” of a region or interest (ROI) of a patient for purposes of imaging organs and other anatomies. The CT modality is commonly employed for purposes of diagnosing disease because such a modality provides precise images that illustrate the size, shape, and location of various anatomical structures such as organs, soft tissues, and bones, and enables a more accurate evaluation of lesions and abnormal anatomical structures such as cancer, polyps, etc.
One method that physicians, clinicians, radiologists, etc., use for diagnosing and evaluating medical conditions is to manually review hard-copies (X-ray films, prints, photographs, etc.) of medical images that are reconstructed from an acquired dataset, to discern characteristic features of interest. For example, CT image data that is acquired during a CT examination can be used to produce a set of 2D medical images (X-ray films) that can be viewed to identify potential abnormal anatomical structures or lesions by a trained physician, clinician, radiologist, etc. However, three-dimensional (3D) renderings of the 2D data typically enable, for example, a trained radiologist to determine whether a suspicious structure is truly an abnormality.
Various image processing systems and tools have been developed to assist physicians, clinicians, radiologists, etc. in evaluating medical images to diagnose medical conditions. For example, computer-aided detection and/or diagnosis (CAD) tools have been developed for various clinical applications to provide automated detection of medical conditions in medical images. In general, CAD systems employ methods and/or techniques for digital signal processing of image data (e.g., CT data) to automatically detect colonic polyps and other abnormal anatomical structures such as lung nodules, lesions, aneurysms, calcification on heart or artery tissue, micro-calcifications or masses in breast tissue, etc. In addition, examination tools have been developed that allow a user to select and annotate portions of the image data. The CAD and examination tools are used to produce locations within the image data that may be examined with both 2D and 3D rendering techniques.
One technique that is used in conjunction with conventional CAD tools is a virtual colonoscopy. When conducting a virtual colonoscopy, a functional model is used to explore a virtual space rendered from three-dimensional (3D) images acquired by a scanner. One such model is a virtual camera, which can be used as a point of reference for the viewer and/or operator, e.g., a radiologist located at a workstation, to explore the virtual space. Typically, the operator has two types of camera control from which they can use to navigate through the virtual space.
The first gives the operator full control of the camera, which allows the operator to manipulate the camera in different positions and orientations to achieve a desired view. In other words, the operator can pilot the camera. This allows the operator to explore a particular section of interest while ignoring other sections. However, complete control of a camera in a large virtual domain is tedious and tiring, and the operator might not view all the important features such as colonic polyps during their exploration.
The second technique of camera control is a pre-planned navigation method, which assigns the camera a predetermined path to take and which does not require intervention by the operator. In other words, the operator has engaged an “autopilot”. This allows the operator to concentrate on the virtual space being viewed, and not have to worry about steering into walls of the environment being examined. However, this second technique may not give the operator sufficient time to fully investigate an interesting area viewed along the flight path.
Accordingly, there is a need for a technique that incorporates data output using CAD methods or data from a manual examination so that a medical expert can navigate through a virtual space and examine detected or marked locations in a short amount of time.